What we know about surface moisture in the MDV
and how to translate it into the approach
- very low overall
- longer wavelenghts can pick it up Predictor: SWIR
- short duration of hydrological events
Soil Moisture generally
Soil Moisture MDV
- soil moisture content important factor of thermal soil properties in the MDV, locations of most active heat-exchange are wetter soils with deeper active layers. Where there is less moisture, active layers are more shallow (most part in the MDV) (Ikard et al. 2009) Valley bottom soils very low SWC, 1% water volume in upper 3cm (Campbell et al. 1998)
- proximity to hydrologic reservoirs spatial control on soil moisture (Wlostowski, Gooseff, and Adams 2018)
- snow patches
- streams
- lakes
- spatially discrete “wet patches” appear darker (Wlostowski, Gooseff, and Adams 2018), mechanisms for their formation: Predictor: optical satellite info
- deliquescence (direct condensation of atmospheric water vapor into saline surficial soil pore spaces) (Joseph S. Levy et al. 2012)
- subsurface routing of meltwater through water tracks (J. S. Levy et al. 2011), coincident with regions of high topographic flow accumulation Predictor: TWI
- wet patch location (Langford, Gooseff, and Lampkin 2015): topography, regional microclimate influence their distribution Predictor: find a way to incorporate information on small depressions (1m DEM)
- soil moisture controls freezing dynamics: based on field observations from sites with natural moisture gradients (active layer monitoring stations: temperature, soil moisture, pore water specific conductance along natural moisture gradient) and a numerical model, magnitude and trend of freezing rates as a function of soil moisture was captured: Soil moisture is a central control of freeze-thaw dynamics of active layer soils in the MDV “..a warmer and more variable climate will … exacerbate freeze-thaw cycling in the driest portions of the landscape.” Freezing events happen mosty in distal soils, i.e. where there is less soil moisture, low water content leads to more active layer freezing events, 0.08 m³/m³ seems to be the defining threshold, whether there will be much or little freezing events (Wlostowski, Gooseff, and Adams 2018)
MDV future climate
- warming in the MDV expected (Chapman and Walsh 2007), near surface warming will increase soil moisture in landscape probably by:
MDV ecosystems
- MDV ecosystems “strongly controlled by abiotic habitat variables” (Wlostowski, Gooseff, and Adams 2018)
- “Nematodes are the most abundant invertebrates found in the Dry Valleys soils and occupy the highest trophic level of a relatively simple soil food chain” (Cary et al. 2010). “Future changes in soil moisture will alter active layer freezing dynamics, possible eliciting shifts in nematode species diversity and abundance” (Wlostowski, Gooseff, and Adams 2018)